The invention relates to a crimping apparatus for crimping a multifilament bundle in a melt spinning process.
In the manufacturing of crimped threads in a melt spinning process crimping of the threads is caused by stuffing the filament bundles to form in each case a thread plug. In this known process, on account of stuffing the filament bundles, the filaments are deposited as loops and arcs and compressed to form the thread plugs, such that, after disintegration of the thread plug, a thread having crimped filaments is produced. The shape of the crimp contained in the filaments here essentially depends on the thermal processing of the thread plug. In order to enable dwelling times for temperature-control of the thread plug that are as long as possible, processing units in which the thread plug produced after stuffing is guided with multiple enlacements on a processing drum have been successful in the prior art.
A crimping apparatus of such type is known from DE 26 32 082, for example. In the known crimping apparatus, a conveyor nozzle, a stuffer box and a processing unit with a processing drum are disposed below one another. In principle, two different positions of the processing drum for receiving and guiding a thread plug guided out of the stuffer box are known here. In a first variant, the axis of the processing drum is oriented substantially horizontally, such that, in the case of multiple enlacements on the circumference of the processing drum, the thread plug has to be guided substantially in the horizontal direction. In this arrangement of the processing drum the windings of the thread plug on the circumference of the drum wall have to be displaced in order to obtain a helical profile of the thread plug on the circumference of the processing drum. Depending on the properties of the drum wall, entanglements of adjacent windings of the thread plug that are more or less intense may arise here. In addition, indexing means are used. In order to axially displace the windings of the thread plug.
In a second variant of the arrangement of the processing drum, the latter, with its axis, is substantially vertically oriented, such that the helically guided thread plugs on the circumference of the processing drum experience natural support of their indexing movement on the circumference of the drum wall. To this extent, comparatively slight indexing forces are required in order to guide the helical profile of the thread plug from the upper end of the processing drum to a lower end of the processing drum. Here, infeeding of the thread plug takes place by an upstream deflection between the stuffer box and the processing chamber. Deflections of this type typically represent a zone which, for temperature control of the thread plug, is uncontrolled and, wherever possible, they should be implemented as short as possible.